Patterns of larval hostplant usage among hawkmoths (Lepidoptera, Sphingidae) from La Réunion, with a comparison of the Mascarenes with other regions of the world

Abstract

The hawkmoth fauna of La Réunion is largely the result of colonization from Mauritius and Madagascar. These species will have arrived with preadapted ecologies, including larval hostplant preferences. Here we investigate these preferences to determine whether they have been conserved or have adapted to local constraints. Using Factorial Correspondence Analysis (FCA), we compare the hostplant spectra of six widespread, polyphagous species (Acherontia atropos, Agrius convolvuli, Coelonia fulvinotata, Daphnis nerii, Hippotion celerio, H. gracilis) and show that generally they utilize the full spectrum of available plant families, any restriction reflecting absence of particular families from La Réunion rather than specialization. However, although Daphnis nerii is found on several Apocynaceae (Nerium, Ochrosia, Pachypodium, Tabernaemontana) on La Réunion, it seems to avoid the abundant species, Thevetia peruviana. Also, Coelonia fulvinotata seems to have developed an association with the invasive alien, Lantana camara, even though several other potential recorded hostplants also occur on the island. In some instances, absence of records in the region may also be due to a lack of field observations. We also analysed the known global host ranges of all species of the 11 sphingid genera on La Réunion. We found principal hostplant associations are conserved across geographical regions, although there may be local preferences, and that these associations may be taxonomic (Acherontia, Agrius and Coelonia are preferentially associated with Euasterids I) or phytochemical (Nephele densoi, associated with two taxonomically distinct lactiferous families).